Arc fault circuit breakers are well known. These breakers comprise contacts that open upon sensing arcing from line to ground, and/or from line to neutral. Arc fault circuit breakers typically use a differential transformer to measure arcing from line to ground. Detecting arcing from line to neutral is accomplished by detecting rapid changes in load current by measuring voltage drop across a relatively constant resistance, usually a bi-metal resistor.
Components of arc fault circuit breakers are generally assembled into separate compartments as defined by their function. More specifically, mechanical components, e.g., load current carrying and switching components, of each pole are assembled into mechanical compartments, while the current sensing components are assembled into an electronics compartment. In order to connect the compartments, the load current of each pole must be routed from the mechanical compartments into the electronics compartment, through appropriate current sensing devices, and back into the mechanical compartments. Additionally sensing lines, e.g., from the bi-metal resistors, must also be routed from the mechanical compartments into the electronics compartment.
Because these circuit breakers sense arc faults, which are essentially short circuits, the connections of the load current carrying components throughout the circuit breaker must be capable of withstanding enormously high surge currents, sometimes in excess of 10,000 amps. The stresses caused by these extremely large surge currents can blow a connection apart that is not manufactured to proper quality standards. This means that during the assembly process, high quality connections, e.g., welds, bolts, or crimps, must be carefully made and inspected in order to survive the extremely high surge currents, and must be completed at a cost and rate that meets the production schedule.
However, in prior art circuit breakers, interconnecting between the various mechanical and electronics compartments, i.e., interconnections, requires partial dis-assembly of the compartments in order for the production tooling to reach them. This procedure provides very little work space, making it difficult, costly and time-consuming to make the high quality interconnections required.
What is needed is a method and apparatus for routing the main current carrying conductor through the current transformer (C/T) with connections that can be both assembled in a production line environment and will maintain the relatively high circuit currents present during shorting.
The above discussed and other drawbacks and deficiencies are overcome or alleviated by an arc fault circuit breaker comprising a plurality of housings having compartments therein. Electrically connected components having interconnecting components, i.e., components which provide electrical interconnections between compartments, are disposed within the compartments. The housings are assembled together to enclose the compartments. Interconnecting components within an enclosed compartment extend through openings in the housings to provide electrical interconnections to the next compartment to be assembled. Therefore, no disassembly of the enclosed compartment is necessary to make the interconnections.
The above discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.